Is the Ketogenic Diet Just Another Low-Carb Diet?

Is the Ketogenic Diet Just Another Low-Carb Diet?

 

Unfortunately, the definition of a low-carbohydrate diet is confounded by the fact that there is no minimum recommended daily allowance for carbohydrates. However, a commonly accepted definition is that a low-carb diet is one that supplies less than 50 percent of its calories from carbohydrates (Feinman et al., 2003). This is in stark contrast to the less-than-50-grams-per-day recommendation for very-low-carbohydrate ketogenic diets. (If the friend we mentioned earlier in the chapter who was eating around 4,500 calories per day used the 50 percent definition, he’d be “low-carb” if he ate 550 grams of carbs a day! We all know that this is anything but low-carb.)

As previously discussed, a ketogenic diet is one in which glucogenic substrates are low enough to force the body to transition from metabolizing glucose to burning fat and subsequently producing ketones. So while a ketogenic diet is low in carbohydrates, a low-carb diet isn’t necessarily ketogenic.

A classic study (Young et al., 1971) demonstrated a clear difference between low-carb and ketogenic diets. Scientists took overweight young men and placed them on “low-carbohydrate” diets consisting of 30, 60, or 100 grams of carbohydrates per day. They found that after nine weeks, the 100-gram group was not in ketosis at all, while the 30-gram group had achieved high levels of ketosis.Moreover, the 30-gram group lost more fat than both the 60-gram group and the 100-gram group despite there being no differences in total calories or protein consumed. This study clearly demonstrates that not all low-carbohydrate diets are the same, and certainly not all are ketogenic.